CN104054282A - Device-to-device communication method and device therefor - Google Patents

Abstract

The present invention relates to a method for performing device-to-device (D2D) communication by a first terminal and a second terminal in a wireless communication system. The method includes: receiving a D2D communication setup response message including resource region information for the D2D communication from a base station; determining, based on the resource region information, whether to switch an operation frequency band of the first terminal from a first frequency band to a second frequency band; and performing the D2D communication with the second terminal at the first frequency band or the second frequency band according to the determined result, wherein either the first frequency band or the second frequency band may be used for transmission in the D2D communication and the other may be used for reception in the D2D communication.

Description

Device-to-device communication method and device thereof

technical field

The present invention relates to a wireless communication system, and more particularly, to a method for performing user equipment (UE) to UE communication and device to device (D2D) communication, a method for supporting D2D communication and a device thereof.

Background technique

In cellular communication, a user equipment (UE) existing in a cell accesses a base station to receive control information for exchanging data from the base station to perform communication, and then transmits and receives data. That is, since the UE transmits and receives data via the base station, the UE transmits data to the base station in order to transmit the data to another cellular UE, and the base station receiving the data transmits the received data to another UE. Since a UE has to transmit data to another UE via a base station, the base station schedules channels and resources for data transmission and reception, and transmits channel and resource scheduling information to each UE. In order to perform UE-to-UE communication via the base station, the base station needs to allocate channels and resources for transmitting and receiving data to each UE. However, in D2D communication, UEs directly transmit and receive signals to desired UEs without using base stations or relays.

If UE-to-UE communication or D2D communication for directly transmitting and receiving data between UEs is performed by sharing resources with an existing cellular network, each UE can perform UE-to-UE communication after resource allocation for UE-to-UE communication. communication. However, in communication between UEs using different frequencies, it is necessary to determine the operating frequency at the time of resource allocation. That is, one of the first UE and the second UE subscribed to different communication operators may move to the operating frequency of the peer UE or perform D2D communication at the third frequency.

Contents of the invention

technical problem

The purpose of the present invention devised to solve the above problem is a method for determining the operating frequency of each UE for D2D communication.

Another object of the present invention devised to solve the problem lies in a method of determining a transmission/reception time of a UE pair for D2D communication.

The technical problems to be solved by the present invention are not limited to the above-mentioned technical problems, and other technical problems not described herein will become apparent from the following descriptions for those skilled in the art.

Technical solutions

The object of the present invention can be achieved by providing a method for performing device-to-device (D2D) communication at a first user equipment (UE) with a second UE in a wireless communication system, the method comprising the steps of: receiving from a base station a D2D communication setting response message for resource area information of D2D communication; determine whether to switch the working frequency band of the first UE from the first frequency band to the second frequency band based on the resource area information; and according to the determination result in the Perform D2D communication with the second UE in the first frequency band or the second frequency band, where one of the first frequency band or the second frequency band is used for sending D2D communication, and the other is used for D2D communication take over.

Additionally or alternatively, transmission of D2D communications may be performed in said first frequency band and reception of D2D communications may be performed in said second frequency band.

Additionally or alternatively, transmission of D2D communications may be performed in said second frequency band and reception of D2D communications may be performed in said first frequency band.

Additionally or alternatively, the resource region information may include information on a period of D2D communication and a frequency of D2D communication.

Additionally or alternatively, the operating frequency band may be switched at a time when the first UE or the second UE switches between sending and receiving D2D communication, the time being included in the resource Indicated by the information about the cycle of D2D communication in the area information.

Additionally or alternatively, the method may further include the step of: switching the working frequency band to the second frequency band indicated by the resource region information.

Additionally or alternatively, the step of performing D2D communication may further include the step of: monitoring a control channel for D2D communication, and receiving control information or sending control information.

Additionally or alternatively, the D2D communication setting response message may further include information on a search space and a scrambling identifier of a control channel used for D2D communication.

In another aspect of the present invention, there is provided herein a UE configured to perform device-to-device (D2D) communication with a peer user equipment (UE) in a wireless communication system, the UE comprising: a radio frequency (RF) unit , the RF unit configured to transmit or receive RF signals; and a processor configured to control the RF unit.

The processor may be configured to receive a D2D communication setting response message including resource area information for D2D communication from the base station via the RF unit, and determine whether to change the operating frequency band of the first UE from the second UE based on the resource area information. switching from one frequency band to a second frequency band, and performing D2D communication with the peer-to-peer UE in the first frequency band or the second frequency band according to the determination result, and wherein, in the first frequency band or in the second frequency band One is used for sending D2D communication, and the other is used for receiving D2D communication.

Additionally or alternatively, transmission of D2D communications may be performed in said first frequency band and reception of D2D communications may be performed in said second frequency band.

Additionally or alternatively, transmission of D2D communications may be performed in said second frequency band and reception of D2D communications may be performed in said first frequency band.

Additionally or alternatively, the resource region information may include information on a period of D2D communication and a frequency of D2D communication.

Additionally or alternatively, the operating frequency band may be switched at a time when the first UE or the second UE switches between transmission and reception, the time may be included in the resource region information The information about the cycle of D2D communication is indicated.

Additionally or alternatively, the operating frequency band may be switched to a second frequency band indicated by the resource region information.

Additionally or alternatively, the processor may monitor a control channel for D2D communication, and receive control information or transmit control information.

Additionally or alternatively, the D2D communication setting response message may further include information on a search space and a scrambling identifier of a control channel used for D2D communication.

In another aspect of the present invention, there is provided herein a method for supporting device-to-device (D2D) communication between a first user equipment (UE) and a second UE at a base station in a wireless communication system, the The method includes the following steps: sending a D2D communication setting response message including resource area information for D2D communication to the first UE or the second UE, wherein the resource area information includes information related to the resource area for D2D communication Information about the first frequency band and the second frequency band corresponding to the working frequency band, wherein one of the first frequency band or the second frequency band is used for sending D2D communication, and the other is used for receiving D2D communication.

In another aspect of the present invention, there is provided herein a base station configured to support device-to-device (D2D) communication between a first user equipment (UE) and a second UE in a wireless communication system, the base station comprising : a radio frequency (RF) unit configured to transmit or receive RF signals; and a processor configured to control the RF unit, wherein the processor is configured to transmit A D2D communication setting response message including resource area information for D2D communication is sent to the first UE or the second UE, wherein the resource area information includes information about the first Information about a frequency band and a second frequency band, wherein one of the first frequency band or the second frequency band is used for sending D2D communication, and the other is used for receiving D2D communication.

It is to be understood that both the foregoing general description and the following detailed description of the invention are exemplary, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed.

Beneficial effect

According to one embodiment of the present invention, the operating frequency of each UE may be determined for D2D communication to easily perform D2D communication. In addition, a transmission/reception time of a UE pair may be determined for D2D communication to efficiently perform D2D communication.

Those skilled in the art will appreciate that effects achievable by the present invention are not limited to those specifically described above, and other advantages of the present invention will be more clearly understood from the following detailed description.

Description of drawings

The accompanying drawings, which are included to provide a better understanding of the invention, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention.

FIG. 1 is a diagram showing an example of a radio frame structure used in a wireless communication system.

FIG. 2 is a diagram illustrating an example of a downlink (DL)/uplink (UL) slot structure in a wireless communication system.

FIG. 3 is a diagram illustrating a downlink subframe structure used in a 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE)(-A) system.

FIG. 4 is a diagram illustrating an uplink subframe structure used in a 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE)(-A) system.

FIG. 5 is a diagram illustrating a network structure of D2D communication according to one embodiment of the present invention.

FIG. 6 is a diagram illustrating a discovery process for D2D communication according to one embodiment of the present invention.

FIG. 7 is a diagram illustrating a setting procedure for D2D communication according to one embodiment of the present invention.

FIG. 8 is a diagram illustrating a D2D cycle according to one embodiment of the present invention.

FIG. 9 is a diagram illustrating an example of indicating a resource region for D2D communication via a control channel of a peer-to-peer base station (eNodeB2) according to one embodiment of the present invention.

FIG. 10 is a diagram illustrating an example of indicating a resource region for D2D communication via a control channel of a peer-to-peer base station (eNodeB2) according to one embodiment of the present invention.

FIG. 11 is a diagram illustrating an example of operating frequency switching for D2D communication according to one embodiment of the present invention.

FIG. 12 is a diagram illustrating an example of operating frequency switching for D2D communication according to one embodiment of the present invention.

FIG. 13 is a diagram illustrating an example of synchronization in a D2D cycle according to one embodiment of the present invention.

FIG. 14 is a diagram illustrating an example of setting a transmission/reception time of each UE according to one embodiment of the present invention.

15 and 16 are diagrams illustrating a D2D setting and communication process according to one embodiment of the present invention.

FIG. 17 is a diagram illustrating a resource renegotiation procedure for D2D setup, D2D communication, and D2D communication between base stations according to one embodiment of the present invention.

FIG. 18 is a block diagram illustrating an apparatus configured to perform operations related to D2D communication according to one embodiment of the present invention.

Detailed ways

Reference will now be made in detail to the preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. The drawings illustrate exemplary embodiments of the invention and provide a more detailed description of the invention. However, the scope of the present invention should not be limited thereto.

In addition, the technologies, devices, and systems described below can be applied to various wireless multiple access systems. For convenience of description, it is assumed that the present invention is applied to 3GPP LTE(-A). However, it should be understood that the technical features of the present invention are not limited to 3GPP LTE(-A). For example, although the following description will be made based on a mobile communication system corresponding to the 3GPP LTE(-A) system, the following description is applicable to other random mobile communication systems other than the system specific to 3GPP LTE(-A).

In some cases, in order to prevent the concept of the present invention from being obscured, structures and devices of known art will be omitted, or will be shown in the form of a block diagram based on main functions of the respective structures and devices. Also, wherever possible, the same reference numbers will be used throughout the drawings and the specification to refer to the same or like parts.

In the present invention, User Equipment (UE) is fixed or mobile. A UE is a device that transmits and receives user data and/or control information by communicating with a base station (BS). The term "UE" may be used with "terminal equipment", "mobile station (MS)", "mobile terminal (MT)", "user terminal (UT)", "subscriber station (SS)", "wireless device", "personal digital assistant (PDA)", "wireless modem", "handheld device" and so on. A BS is typically a fixed station that communicates with a UE and/or another BS. A BS exchanges data and control information with a UE and another BS. The term "BS" may be used with "Advanced Base Station (ABS)", "Node B", "Evolved Node B (eNB)", "Basic Transceiver System (BTS)", "Access Point (AP)", "Processing Server ( PS)" etc. instead. In the following description, BSs are collectively referred to as eNBs.

In the present invention, PDCCH (Physical Downlink Control Channel)/PCFICH (Physical Control Format Indicator Channel)/PHICH (Physical Hybrid Automatic Repeat Request Indicator Channel)/PDSCH (Physical Downlink Shared Channel) refer to A set of time-frequency resources or resource elements carrying DCI (Downlink Control Information)/CFI (Control Format Indicator)/Downlink ACK/NACK (Acknowledgment/Negative ACK)/Downlink data. In addition, PUCCH (Physical Uplink Control Channel)/PUSCH (Physical Uplink Shared Channel)/PRACH (Physical Random Access Channel) refer to carrying UCI (Uplink Control Information)/Uplink Data/Random Access Channel respectively. A set of time-frequency resources or resource elements of an incoming signal. In the present invention, time-frequency resources or resource elements (REs) allocated to or belonging to PDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH are referred to as PDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH RE or PDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH resources. In the following description, transmission of PUCCH/PUSCH/PRACH by UE is equivalent to transmission of uplink control information/uplink data/random access signal through PUCCH/PUSCH/PRACH or on PUCCH/PUSCH/PRACH. In addition, transmission of PDCCH/PCFICH/PHICH/PDSCH by eNB is equivalent to transmission of downlink data/control information through PDCCH/PCFICH/PHICH/PDSCH or on PDCCH/PCFICH/PHICH/PDSCH.

In addition, in the present invention, the cell-specific reference signal (CRS)/demodulation reference signal (DMRS)/channel state information reference signal (CSI-RS) time-frequency resources (or REs) respectively indicate that they can be allocated to CRS/DMRS /CSI-RS or REs for CRS/DMRS/CSI-RS, or time-frequency resources (or REs) carrying CRS/DMRS/CSI-RS. In addition, subcarriers including CRS/DMRS/CSI-RS REs may be referred to as CRS/DMRS/CSI-RS subcarriers, and OFDM symbols including CRS/DMRS/CSI-RS REs may be referred to as CRS/DMRS/CSI-RS subcarriers. RS symbol. In addition, in the present invention, an SRS time-frequency resource (or RE) may mean a time-frequency resource (or RE) transmitted from a user equipment to a base station so that the base station can carry a Sounding Reference Signal (SRS) for A state of an uplink channel formed between the user equipment and the base station is measured. A Reference Signal (RS) means a signal of a special waveform that is predefined and well known by user equipment and base stations, and may be called a pilot.

In the present invention, a cell refers to a specific geographical area where one or more nodes provide communication services. Accordingly, communication with a specific cell may mean communication with an eNB or a node providing a communication service to the specific cell. A downlink/uplink signal of a specific cell refers to a downlink/uplink signal from/to an eNB or a node providing a communication service to a specific cell. A cell that provides uplink/downlink communication services to a UE is called a serving cell. In addition, the channel state/quality of a specific cell refers to the channel state/quality of a channel or a communication link generated between an eNB or a node providing a communication service to a specific cell and a UE.

FIG. 1 shows an exemplary radio frame structure used in a wireless communication system. Figure 1(a) shows the frame structure of Frequency Division Duplex (FDD) used in 3GPP LTE/LTE-A, and Figure 1(b) shows the frame structure of Time Division Duplex (TDD) used in 3GPP LTE/LTE-A frame structure.

Referring to FIG. 1, a radio frame used in 3GPP LTE/LTE-A has a length of 10ms (307200Ts) and includes 10 subframes of equal size. The 10 subframes in a radio frame can be numbered. Here, Ts represents the sampling time, and is expressed as Ts=1/(2048*15kHz). Each subframe has a length of 1 ms and includes two slots. The 20 slots in a radio frame may be numbered sequentially from 0 to 19. Each slot has a length of 0.5ms. The time for transmitting a subframe is defined as a Transmission Time Interval (TTI). Time resources can be distinguished by radio frame number (or radio frame index), subframe number (or subframe index) and slot number (or slot index).

A radio frame may be configured differently according to a duplex mode. In the FDD mode, downlink transmission is distinguished from uplink transmission by frequency, and thus, a radio frame includes only one of a downlink subframe and an uplink subframe in a specific frequency band. In TDD mode, downlink transmission is distinguished from uplink transmission by time, and thus, a radio frame includes both downlink subframes and uplink subframes in a specific frequency band.

Table 1 shows DL-UL configurations of subframes in a radio frame in TDD mode.

[Table 1]

In Table 1, D represents a downlink subframe, U represents an uplink subframe, and S represents a special subframe. The special subframe includes three fields: DwPTS (Downlink Pilot Time Slot), GP (Guard Period) and UpPTS (Uplink Pilot Time Slot). DwPTS is a period reserved for downlink transmission, and UpPTS is a period reserved for uplink transmission. Table 2 shows special subframe configurations.

Fig. 2 shows an exemplary downlink/uplink slot structure in a wireless communication system. Specifically, FIG. 2 shows a resource grid structure in 3GPP LTE/LTE-A. There is one resource grid per antenna port.

Referring to FIG. 2 , a slot includes a plurality of OFDM (Orthogonal Frequency Division Multiplexing) symbols in the time domain and a plurality of Resource Blocks (RBs) in the frequency domain. An OFDM symbol may refer to a symbol period. The signal transmitted in each time slot can be passed by the subcarriers and A resource grid composed of OFDM symbols is represented. here, Indicates the number of RBs in the downlink slot, Indicates the number of RBs in an uplink slot. and Depends on the DL transmission bandwidth and the UL transmission bandwidth respectively. Indicates the number of OFDM symbols in the downlink slot, Indicates the number of OFDM symbols in an uplink slot. in addition, Indicates the number of subcarriers constituting one RB.

According to a multiple access scheme, OFDM symbols may be referred to as SC-FDM (Single Carrier Frequency Division Multiplexing) symbols. The number of OFDM symbols included in a slot may depend on channel bandwidth and the length of a cyclic prefix (CP). For example, a slot includes 7 OFDM symbols in case of a normal CP and includes 6 OFDM symbols in case of an extended CP. Although FIG. 2 illustrates a subframe in which a slot includes 7 OFDM symbols for convenience, embodiments of the present invention are equally applicable to subframes having a different number of OFDM symbols. Referring to Figure 2, each OFDM symbol in the frequency domain includes subcarriers. Subcarrier types may be classified into data subcarriers for data transmission, reference signal subcarriers for reference signal transmission, and null subcarriers for guard bands and direct current (DC) components. A null subcarrier for the DC component is a subcarrier that is still unused and is mapped to a carrier frequency (f0) during OFDM signal generation or upconversion. This carrier frequency is also called the center frequency.

RB consists of the time domain (e.g., 7) consecutive OFDM symbols and the frequency domain (eg, 12) contiguous subcarriers are defined. For reference, resources composed of OFDM symbols and subcarriers are called resource elements (REs) or tones. Therefore, RB consists of composed of REs. Each RE in the resource grid may be uniquely defined by an index pair (k,l) in a slot. Here, k is the range from 0 to index in the range, l is 0 to index in the range.

occupies the subframe Two RBs that are consecutive subcarriers and are respectively arranged in two slots of a subframe are called a physical resource block (PRB) pair. Two RBs constituting a PRB have the same PRB number (or PRB index). A Virtual Resource Block (VRB) is a logical resource allocation unit for resource allocation. A VRB has the same size as a PRB. According to the mapping scheme of VRBs to PRBs, VRBs can be divided into centralized VRBs and distributed VRBs. A localized VRB is mapped to a PRB such that a VRB number (VRB index) corresponds to a PRB number. That is, n _PRB =n _VRB is obtained. from 0 to Number the centralized VRB, and get Therefore, according to the centralized mapping scheme, VRBs with the same VRB number are mapped to PRBs with the same PRB number at the first and second slots. On the other hand, distributed VRBs are mapped to PRBs through interleaving. Accordingly, VRBs with the same VRB number may be mapped to PRBs with different PRB numbers at the first and second slots. Two PRBs respectively located at two slots of a subframe and having the same VRB number will be referred to as a pair of VRBs.

FIG. 3 shows a downlink (DL) subframe structure used in 3GPP LTE/LTE-A.

Referring to FIG. 3, a DL subframe is divided into a control region and a data region. A maximum of three (four) OFDM symbols located at the front of the first slot within a subframe correspond to a control region to which a control channel is allocated. A resource region available for PDCCH transmission in a DL subframe is hereinafter referred to as a PDCCH region. The remaining OFDM symbols correspond to a data region to which a physical downlink shared channel (PDSCH) is allocated. A resource region available for PDSCH transmission in a DL subframe is hereinafter referred to as a PDSCH region. Examples of downlink control channels used in 3GPP LTE include Physical Control Format Indicator Channel (PCFICH), Physical Downlink Control Channel (PDCCH), Physical Hybrid ARQ Indicator Channel (PHICH), etc. The PCFICH is sent at the first OFDM symbol of a subframe and carries information about the number of OFDM symbols used for transmission of control channels within the subframe. The PHICH is a response to uplink transmission and carries a HARQ acknowledgment (ACK)/negative acknowledgment (NACK) signal.

The control information carried on the PDCCH is called downlink control information (DCI). DCI contains resource allocation information and control information for a UE or a group of UEs. For example, the DCI includes transmission format and resource allocation information of the downlink shared channel (DL-SCH), transmission format and resource allocation information of the uplink shared channel (UL-SCH), paging information of the paging channel (PCH) , system information on DL-SCH, information on resource allocation of upper layer control messages (for example, random access responses sent on PDSCH), transmission control command sets for each UE in the UE group, transmission power control commands, Information on activation of Voice over IP (VoIP), Downlink Assignment Index (DAI), etc. The transmission format and resource allocation information of DL-SCH are also called DL scheduling information or DL grant, and the transmission format and resource allocation information of UL-SCH are also called UL scheduling information or UL grant. The size and purpose of the DCI carried on the PDCCH depends on the DCI format, and its size can vary according to the coding rate.

Multiple PDCCHs may be sent in the PDCCH region of a DL subframe. A UE may monitor multiple PDCCHs. The BS decides the DCI format according to the DCI to be transmitted to the UE, and attaches a Cyclic Redundancy Check (CRC) to the DCI. The CRC is masked with an identifier such as a Radio Network Temporary Identifier (RNTI) according to the owner or usage of the PDCCH. If the PDCCH is for a specific terminal, the CRC may be masked using the terminal's Cell-RNTI (C-RNTI). Alternatively, if the PDCCH is used for a paging message, the CRC may be masked with a paging indicator identifier (P-RNTI). If the PDCCH is used for system information (more specifically, a system information block (SIB)), the CRC may be masked with a system information identifier and a system information RNTI (SI-RNTI). If the PDCCH is used for the random access response, the CRC may be masked using a random access-RNTI (RA-RNTI). For example, CRC masking (or scrambling) involves an XOR operation of CRC and RNTI at the bit level.

The PDCCH is sent on one Control Channel Element (CCE) or an aggregation of multiple consecutive CCEs. A CCE is a logical allocation unit for providing a coding rate to a PDCCH based on a radio channel state. CCEs correspond to a plurality of Resource Element Groups (REGs). For example, one CCE corresponds to nine REGs, and one REG corresponds to four REs. Four QPSK symbols are mapped to each REG. REs occupied by the RS are not included in the REG. Therefore, the number of REGs within a given OFDM symbol varies according to the presence/absence of RS. The REG concept is also used for other DL control channels (ie, PCFICH and PHICH). The DCI format and the number of DCI bits are determined according to the number of CCEs.

CCEs are numbered and used consecutively. To simplify decoding, a PDCCH with a format consisting of n CCEs may only start with CCEs whose number corresponds to a multiple of n. The number of CCEs (ie, CCE aggregation level) used to transmit a specific PDCCH is determined by the BS according to a channel state. For example, one CCE may be sufficient in case of a PDCCH for a UE with a good DL channel (eg, a UE adjacent to the BS). However, in case of PDCCH for UEs with poor channels (eg, UEs located at the cell edge), 8 CCEs are required to obtain sufficient robustness.

FIG. 4 is a diagram illustrating an example of an uplink subframe structure used in a 3GPP LTE(-A) system.

Referring to FIG. 4 , a UL subframe may be divided into a control region and a data region in the frequency domain. One or more Physical Uplink Control Channels (PUCCHs) may be allocated to the control region to carry Uplink Control Information (UCI). One or more Physical Uplink Shared Channels (PUSCHs) may be allocated to the data region of the UL subframe to carry user data. A control region and a data region in a UL subframe are also referred to as a PUCCH region and a PUSCH region, respectively. A Sounding Reference Signal (SRS) may be allocated to the data region. The SRS is transmitted on the last OFDM symbol of the UL subframe in the time domain, and is transmitted on the data transmission band (ie, data region) of the UL subframe. SRSs of multiple UEs transmitted/received on the last OFDM symbol of the same subframe are distinguished according to frequency position/sequence.

If the UE adopts the SC-FDMA scheme in UL transmission in order to maintain the single carrier characteristic, in the 3GPP LTE Release 8 or Release 9 system, PUCCH and PUSCH cannot be sent on one carrier at the same time. In a 3GPP LTE Release 10 system, support for simultaneous transmission of PUCCH and PUSCH may be indicated by higher layers.

In a UL subframe, subcarriers away from direct current (DC) subcarriers are used as a control region. In other words, subcarriers located at both ends of the UL transmission bandwidth are used to transmit uplink control information. The DC subcarrier is a component that is not used for transmitting signals and is mapped to the carrier frequency f0 in the up-conversion process. A PUCCH for one UE is allocated to an RB pair belonging to resources operating in one carrier frequency, and RBs belonging to the RB pair occupy different subcarriers in two slots. The allocated PUCCH is represented by the frequency hopping of the RB pair allocated to the PUCCH at the slot boundary. If no frequency hopping is applied, the RB pair occupies the same subcarrier.

The size and usage of UCI carried by one PUCCH may vary according to a PUCCH format, and the size of UCI may vary according to a coding rate. For example, the following PUCCH formats can be defined.

[Table 2]

Referring to Table 2, PUCCH format 1/1a/1b is used to transmit ACK/NACK information, PUCCH format 2/2a/2b is used to carry CSI such as CQI/PMI/RI, and PUCCH format 3 is used to transmit ACK/NACK information.

FIG. 5 is a diagram illustrating a network structure of D2D communication according to one embodiment of the present invention. D2D communication refers to direct communication between a transmitting UE (UE1) and a receiving UE (UE2), both of which are within their transmission coverage, without the participation of a base station (eNodeB). Wireless communication scheme. The present invention particularly proposes a D2D communication method when UE1 and UE2 subscribe to different wireless communication operators. Generally, since each wireless communication operator provides communication at different frequencies, UE1 and UE2 respectively subscribed to different communication operators work at different frequencies in general communication (ie, communication with eNodeB).

UE1 is served by a first base station (eNodeB1 ) connected to an Operator Management Entity (OME) of a first operator and UE2 is served by a second base station (eNodeB2) connected to an OME of a second operator. The OME of the first operator and the OME of the second operator are connected to each other via an interface A. FIG. UE1 and UE2 communicate with their base station at frequencies f1 and f2 respectively. Since UE1 and UE2 perform D2D communication, each UE includes a transmitter and a receiver capable of operating at frequencies f1 and f2.

FIG. 6 is a diagram illustrating a discovery process of D2D communication according to one embodiment of the present invention. For D2D communication between UEs, a process of discovering counterpart UEs (ie, peer UEs) is required. Peer-to-peer UE discovery is a process of querying peer-to-peer UEs to check whether the peer-to-peer UE has D2D communication capability and to determine the operator to which the network to which the peer-to-peer UE is connected or subscribed belongs.

For peer UE discovery, UE 110 may discover peer UEs via an eNodeB. This discovery method is effectively used to discover UEs served by another operator. For peer-to-peer UE discovery, UE 110 may send a D2D discovery request message to eNodeB 120 (S601). The D2D Discovery Request message may include the following information elements.

– UE ID

– UE MAC address

– Peer UE ID

The UE ID is the identifier (ID) of the UE (i.e., the discovery requester) for sending the D2D discovery request message, the UE MAC address is the MAC address of the UE, and the peer UE ID is the peer UE (specified by the discovery requester). D2D communication partner) ID.

The eNodeB 120 having received the request message from the UE 110 may send a message for inquiring about the subscription of the peer UE to the first OME 30 of the operator with which it is registered ( S602 ).

The OME may perform access control and data routing/forwarding functions between networks while acting as a gateway between networks of different operators. In addition, the OME may store information about UEs subscribed to an operator with which it is registered, or have an interface with a location server configured to store information about UEs. For example, in an LTE(-A) system, an OME may be defined as a Mobility Management Entity (MME) or a Serving Gateway (SGW), or may be defined as a logical entity having an interface with the MME or the SGW. The query (or query message) sent by eNodeB1 may include the peer UE's ID and/or the eNodeB1's ID.

When receiving the query message, the first OME 30 may check which operator the peer UE (in this embodiment, the UE 260 ) subscribes to ( S603 ). In order to check which operator the peer-to-peer UE subscribes to, if the first OME 30 knows information about the operator of the UE 260, the first OME 30 may forward the query message to the OME of the operator of the UE 260 (in this embodiment, the second OME40) (S604). The transmitted query messages are defined in the interface A between OMEs and are called A queries. The A-query may also include information about the first OME 30 that sent the A-query.

When receiving the A query from the first OME 30 (which is another operator's OME), the second OME 40 may check whether the UE 260 is subscribed or has D2D communication capability. The UE registers user-related information and subscription-related information with the OME or the location server when it first tries to access the network. The user-related information may include UE ID, D2D capability, or information indicating whether to allow the D2D function, and the subscription-related information may include operator information. Accordingly, the second OME 40 may detect information on the UE 260 therefrom or from a location server (S605).

If the UE 260 does not subscribe to the second OME 40 or has no D2D capability, or if the D2D function is not allowed, the second OME 40 may discard the A query from the first OME 30 or send a response message indicating that the query request failed. If the UE 260 subscribes to the second OME 40, the second OME 40 may transmit a query message to a candidate eNodeB that provides services to the peer UE (S606). Information on candidate eNodeBs may be managed by OME or a location server. When receiving the query message, the eNodeB 250 may broadcast a D2D discovery request message (S607).

The D2D discovery request message may include the ID of the UE 260 (ie, the ID of the peer UE). For example, a PDCCH having an RNTI value corresponding to the D2D discovery request is included in a downlink subframe transmitted through the request message, and thus, the ID of the UE 260 may be transmitted in a region indicated by the PDCCH. UE260 may monitor PDCCH from eNodeB50 and check if a D2D discovery request is made. UE260 should monitor the RNTI value allocated to the D2D discovery request in the PDCCH. If a D2D discovery request is made, UE2 may check whether the ID of the UE of the area indicated by the PDCCH matches its ID. In order to reduce the overhead for monitoring the PDCCH, if there is a UE ID among the IDs of UEs managed by the eNodeB 250 that matches the ID of the peer UE included in the query message, the D2D Discovery Request message may be sent via UE-specific signaling sent directly to the UE.

When the ID value of the peer UE of the D2D discovery request message matches the ID of UE2, the UE 260 may send a D2D discovery response message as a response to the request (S608). The D2D discovery response message may include the ID of the responder (UE 260 in this embodiment). When receiving the D2D discovery response message, the eNodeB250 may send the D2D discovery response message including its ID to the second OME40 subscribed by the eNodeB2 (S609). When receiving the D2D discovery response message, the second OME 40 may determine that a peer UE for D2D communication has been successfully discovered, and send an A response message to the first OME 30 ( S610 ). The A response message may include operator identifier information managed by the second OME 40, frequency information managed by the operator, operating frequency information of the eNodeB providing service to the peer UE (or operating frequency information of the eNodeB providing service to the peer UE Among them, frequency resources allocated for D2D communication).

When receiving the A response message, the first OME 30 may send the response message to the eNodeB1 20 (S611). The response message may include IDs of peer UEs, peer eNodeBs, and/or peer OMEs (in this embodiment, UE2 60, eNodeB2 50, and second OME 40) and information related to operating frequencies.

When receiving the response message, eNodeB1 20 may send the D2D discovery response message to UE1 10 (S612). The D2D Discovery Response message may include the following information elements.

– Peer UE ID

– peer UE MAC address

– Peer UE operator information (e.g. carrier frequency and/or operating bandwidth, cell ID, etc.)

– Peer UE operating frequency (and/or bandwidth allocated for D2D communication)

Peer UE ID is the identifier of the peer UE (i.e., the discovery responder) used to send the D2D discovery response message, peer UE MAC address is the MAC address of the peer UE, peer UE operator information is the same as the peer UE The information about the operator subscribed by the UE, and the peer-to-peer UE operating frequency is the operating frequency of the peer-to-peer UE.

In the D2D communication discovery process, a timeout value may be set in order to prevent the UE, eNodeB and OME from continuing to stand by until a response is received. The timeout value refers to the time interval during which the UE1 10, eNodeB1 20 and first OME 30 corresponding to the requesting entity stand by before receiving a response to the A query message. When the timeout value expires before a response is received, the request is considered to have failed. The timeout value may be explicitly included in each message to be sent with other information elements, or may be configured individually in each entity to use a predetermined value.

If the D2D communication partner finds that the process is complete, a link setting procedure for D2D communication is performed. FIG. 7 is a diagram illustrating a setting procedure for D2D communication according to one embodiment of the present invention. In FIG. 7 , S701 and S702 correspond to S601 and S612 of FIG. 6 , and description thereof will be omitted.

UE11 may send a D2D setup request message to eNodeB21 (S703). At this time, UE11 may send a D2D discovery response message or receive a D2D discovery response message. That is, UE11 may be UE110 or UE260 shown in FIG. 6 .

The D2D Setup Request message may include the following information elements.

– UE ID

– UE operator information

– Peer UE ID

– Peer UE operator information

– D2D period consisting of 3 fields: start time, period and interval (optional)

The UE ID is the IE of the UE (that is, the requester) used to send the D2D setup request message, the UE operator information is information related to the operator subscribed by the UE, and the peer UE ID is the ID of the peer UE for D2D communication ID, peer-to-peer UE operator information is information related to the operator subscribed by the peer-to-peer UE, and the D2D cycle is optional and corresponds to the cycle of D2D communication.

When receiving the D2D setting request message, the eNodeB21 may allocate a D2D resource area and set a period of D2D communication. That is, the eNodeB21 can allocate time-frequency resources for D2D communication. The cycle of D2D communication set by the eNodeB 21 may be equal to the D2D cycle field included in the D2D setting request message. The eNodeB21 may transmit a D2D setup request message to the UE11 in response to the D2D setup request message (S704). In addition, the eNodeB 21 may transmit a D2D setup response message including information on a period of D2D communication and a D2D resource area to a peer eNodeB (not shown).

The D2D Setup Response message may include the following information elements.

-status code

– Peer UE ID

– D2D period consisting of 3 fields: start time, period and interval

– D2D resource area

The status code indicates whether the D2D setup request is permitted or failed, the peer UE ID indicates the ID of the peer UE, the D2D cycle indicates the cycle information of D2D communication, and the D2D resource area indicates the time-frequency resource area used for D2D communication. The D2D resource region may include carrier information allocated for D2D communication. Also, if there is a control channel for D2D communication, the D2D resource region may include information related to the control channel. Information related to the control channel may include carrier information and/or search space information. UE11 or peer UE61 may switch to the frequency of the carrier indicated in the D2D resource region to monitor the control channel.

More specifically, the carrier information may be a frequency managed by an operator subscribed by the peer UE or a third frequency licensed to be used by the UE11 and the peer UE61, or an unlicensed frequency. In addition, the control channel-related information refers to information on a resource region in which a control channel is transmitted. The control channel may be sent by the peer eNodeB, or may be sent directly by the peer UE. The control channel related information may include the carrier frequency on which the control channel is transmitted. The carrier frequency at which the control channel is transmitted may be equal to the information on the operating frequency of the peer UE included in the D2D discovery response message. At this time, the D2D resource region may include search space information of the control channel and an RNTI value of the control channel, so as to enable the UE 11 to decode the control channel at the carrier frequency used for D2D communication.

Alternatively, UE11 may immediately perform synchronization with UE61 without detecting or decoding a control channel, and transmit and receive data for D2D communication. In this case, the D2D resource region may include a seed value (for example, C-RNTI) for generating a signal or a location of a time/frequency resource for transmitting a data channel or a synchronization signal.

The D2D period is a time interval when UE11 stops communicating with eNodeB21 and communicates with peer UE61. The reason for setting the D2D period is because UE11 can perform access with one transmitter and receiver at multiple operator frequencies, but the transmitter and receiver are designed to work only at one operator frequency at a time point , or UE11 has a transmitter and receiver capable of operating on two or more operator frequencies, but simultaneous transmission and reception on two operator frequencies can result in a transmission on one frequency being Interference between receptions.

FIG. 8 is a diagram illustrating a D2D cycle according to one embodiment of the present invention. FIG. 8 shows that the operating frequency of the UE is switched to the eNodeB frequency for communication with the eNodeB in the access cycle and switched to the D2D frequency for D2D communication in the D2D cycle.

UE11 stops communication with eNB21 for D2D communication and acquires resources for D2D communication. At this time, the UE 11 may start D2D communication in a state where the link with the eNodeB 21 is disconnected, or may perform D2D communication in a state where the link is maintained. If the link is maintained, the UE11 may not perform communication with the eNodeB21 during the D2D communication cycle. Therefore, while UE11 is operating for D2D communication, eNodeB21 does not schedule data transmission between eNodeB21 and UE11.

If the UE 11 includes a transmitter and receiver capable of operating at dual radio frequencies and performs simultaneous transmissions at different operator frequencies, the D2D Period information element may not be included in the D2D Setup Request/Response message. In this case, one radio frequency can be used for communication with eNodeB21 and another radio frequency can be used for D2D communication. If the D2D period is not included as an information element, it may be determined that the radio frequency for D2D communication may be continuously used.

Even when the UE 11 can perform simultaneous transmissions at different operator frequencies, the D2D cycle information element may be included in the D2D setup request/response message. In this case, the radio frequency unit used for D2D communication sleeps during the access period. That is, in order to save the battery of UE11, the RF unit of the frequency band used for D2D communication is turned off during the access period.

When receiving the D2D setup response message, UE11 may send a D2D setup confirmation message to eNodeB21 (S705). The D2D Setup Confirm message may include the following information elements.

-status code

The status code indicates whether the D2D setup request is permitted or failed.

In addition, when the D2S setup response message is received and the status code is permitted, the UE 11 may switch its frequency to the frequency indicated by the peer UE operating frequency in the area set as the D2D cycle. At this time, the UE 11 may be configured to notify a value indicating a D2D cycle of the D2D setup response message via radio resource control (RRC) signaling. UE11 switches its frequency to the frequency specified in a certain cycle (time or interval) according to the new settings. The UE 11 whose frequency has been switched can receive the control channel at the switched frequency and perform D2D data communication (S706 and S708). UE11 may perform data communication with eNodeB21 in the access cycle (S707).

Steps S706, S707 and S708 may be implemented in other forms than those shown in FIG. 7, and at least one step may be omitted.

If the UE11 includes a transmitter and a receiver capable of operating on dual radio frequencies and performs simultaneous transmissions on different operator frequencies, the D2D period of the UE11 needs to be set. Therefore, UE11 may switch its frequency to the frequency indicated by the peer UE operating frequency information element immediately after the D2D Setup Confirm message is sent or at a desired time. When the frequency switch is complete, the control channel can be monitored.

In a system having an asynchronous distributed coordination function (DCF)-based protocol (eg, IEEE802.11), when a UE performs frequency switching, the medium may be kept in an idle mode at the switched frequency to perform D2D communication. In contrast, in a synchronous system such as 3GPP LTE(-A), UE reception (or transmission) time and peer UE transmission (or reception) time should be set separately to match each other. Therefore, OMEs need to negotiate with each other such that D2D data transmission and reception are performed in the negotiated resource region, and need to signal the negotiation result.

Also, the carrier frequency indicated in the D2D resource region may not match the operator frequency of UE2 (peer UE). For example, D2D control and D2D data may be sent on the extension carrier of eNodeB2 (peer eNodeB).

Also, in the D2D setup process, eNodeB2 transmits a D2D setup response message including information on the same D2D resource region as the resource region transmitted from eNodeB1 to UE1 in a non-requested state. UE2 receiving the unsolicited D2D Setup Response message may broadcast an advertisement signal including its ID. UE2 receiving the advertisement signal directly establishes a link with the peer UE and exchanges data. At this time, the advertisement signal may include resource area information for D2D data transmission.

The D2D communication processing S706 and S708 will now be described in more detail. UE11 switches its operating frequency to the operating frequency of the peer-to-peer UE in the D2D period. Then, UE11 detects a synchronization signal (SS) transmitted by a peer eNodeB (eNodeB serving the peer UE) at this frequency, and synchronizes with the peer eNodeB. Subsequently, the UE 11 can decode the broadcast channel (BCH) sent by the peer eNodeB to receive the broadcast information (main/system information) of the peer eNodeB.

The UE 11 synchronized with the peer eNodeB can acquire information about the D2D resource region from the peer eNodeB. The UE 11, which has switched its operating frequency to the operator frequency of the peer UE, receives the control channel from the peer eNodeB. The control channel includes information on resource regions allocated for D2D data transmission and reception. The control channel can be decoded by both the UE11 and the peer UE61, and data transmission and reception between UEs is performed in the resource region indicated by the control channel (S706 and S708).

For example, information on D2D resource regions may be transmitted via D2D PDCCH. Here, D2D PDCCH is configured for D2D communication, and refers to a channel transmitted from eNodeB to UE11 and peer UE61 participating in D2D communication. The D2D PDCCH includes resource allocation information for D2D communication, and may follow the configuration and format of a PDCCH for general LTE(-A) communication between UE and eNodeB unless otherwise specified.

UE11 must acquire information for decoding D2D PDCCH in advance. Information for decoding includes information on a resource region (eg, PDCCH search space) where a control channel is transmitted and scrambling ID (eg, D2D-RNTI) information required for decoding. These information can be acquired via the D2D Resource Area Information element included in the D2D Setup Response message in the setup process for D2D communication. The Peer UE 61 may acquire related information in the process of connecting to a Peer eNodeB (eNodeB that provides services to the Peer UE) (not shown) or via an RRC connection.

For example, in Fig. 7, the UE may receive the control channel (or D2D PDCCH) for D2D communication sent by the peer eNodeB after switching to f2 (the operating frequency of the peer UE61). Downlink Control Information (DCI) of a control channel for D2D communication may be defined in a new DCI format. The D2D DCI format may include information on a downlink reception resource region and an uplink transmission resource region of the peer UE 61. The peer UE61 may send data to the UE11 via the downlink of the peer UE61, and the peer UE61 may receive data from the UE11 via the uplink of the peer UE61. The downlink and uplink of UE11 correspond to the uplink and downlink of peer UE61. That is, in the embodiments of the present invention, the uplink used for D2D communication refers to a link used for sending data at one UE to a peer UE, and the downlink used for D2D communication refers to a link used for A link where one UE receives data from a peer UE.

When the UE11 receives the D2D PDCCH from the peer eNodeB, it can confirm the uplink/downlink resource area of the peer UE61. Therefore, the UE11 can transmit data to the peer UE61 in the reception area of the peer UE61 and receive data from the peer UE61 in the transmission area of the peer UE61.

FIG. 9 is a diagram illustrating an example of indicating a resource region for D2D communication via a control channel of a peer-to-peer base station (eNodeB2) according to one embodiment of the present invention. In order to decode PDCCH, UE should know the configuration of search space (SS). The SS refers to information on a candidate resource block or a candidate supporting block group for transmitting a UE-specific PDCCH in the PDCCH resource region.

Since the connection with eNodeB2 is established, UE2 can acquire the configuration of the SS via RRC signaling. If the connection with eNodeB2 is established, UE1 can acquire the configuration of the SS via RRC signaling similarly to UE2. If the connection with eNodeB2 is not established, UE1 should obtain the information about the SS of D2D PDCCH via the D2D Setup Response message before switching to the operating frequency of UE2. In this case, the information about SS is semi-static. UE1 and UE2 can blindly decode the PDCCH allocated for D2D communication in the SS of the D2D PDCCH.

FIG. 10 is a diagram illustrating an example of indicating a resource region for D2D communication via a control channel of a peer-to-peer base station (eNodeB2) according to one embodiment of the present invention. Information on the D2D resource region may be transmitted via an enhanced PDCCH (ePDCCH). The ePDCCH is a PDCCH extended to the data region of the downlink subframe, and more control channels can be transmitted via the downlink subframe. Therefore, ePDCCH may exist in a PDSCH region (ie, data region) of an existing downlink subframe. In this case, SS refers to the candidate resource block or resource block group region of D2D ePDCCH. The SS of D2D ePDCCH can be configured via RRC signaling similarly to D2D PDCCH. UE1 that is not RRC connected to eNodeB2 can acquire information on the SS of D2DePDCCH via the D2D Setup Response message. In this case, the information about SS is semi-static.

When the information on the SS or the configuration of the SS is updated, eNodeB2 may notify eNodeB1 of the updated information or configuration. UE1 may receive information on SS or configuration of SS from eNodeB1 in the access cycle of FIG. 7 . Additionally, during the D2D cycle, UE1 may receive updated information or configuration from UE2 via a direct link with UE2. In other words, in the D2D period, UE2 can send the D2D ePDCCH to UE1. When receiving the D2D ePDCCH, UE1 may transmit data for D2D communication to UE2 in the resource region allocated based on the D2D ePDCCH.

Then, once UE1 and UE2 know the SS of the D2D ePDCCH, they can blindly decode the D2DePDCCH in the region of the SS. The D2D ePDCCH may include transport format information and/or resource allocation information for the D2D uplink (link from UE2 to UE1) and D2D downlink (link from UE1 to UE2). Each transmission region may be divided into uplink and downlink subframes as shown in FIG. 10( a ), or may be defined in an uplink subframe as shown in FIG. 10( b ).

FIG. 11 is a diagram illustrating an example of operating frequency switching for D2D communication according to one embodiment of the present invention. Even when each UE for D2D communication includes a transmitter/receiver capable of operating at a plurality of different operator frequencies, transmission and reception at all operator frequencies are not necessarily allowed. For example, due to the operator's payment policy, the UE's data transmission is only allowed at frequencies managed by the operator to which the UE subscribes. When a UE that does not subscribe to an operator uses the operator's frequency for D2D communication without the operator's management system, the operator cannot require the UE to pay, and the UE that does not subscribe to the operator is not allowed to send and receive.

Accordingly, if a UE that will perform D2D communication is subscribed to a different operator, the UE may receive data but may not transmit data at a frequency of the different operator. At this point, the UE may be allowed to receive data on another operator's frequency, and thus payment may be required from the sender UE.

Therefore, for D2D communication, the UE operates at an operating frequency for data transmission and an operating frequency for data reception. For example, a UE operates on its operator's frequency and operates on the peer UE's operator's frequency. At this point, the UE can send ACK/NAK along with data. ACK/NAK pertains to data received on the peer UE's operator frequency.

In FIG. 11, the operating frequencies of the transmitting operation and the receiving operation are different. UE1 and UE2 send data to each other using a D2D communication method. The downlink frequency and uplink frequency of UE1 are f1D and f1u respectively, and the downlink frequency and uplink frequency of UE2 are f2D and f2u respectively. In addition to sending uplink data to eNodeB under flu, UE1 can send D2D data to UE2. At this time, the resource region for data transmission to UE2 may be defined to be orthogonal to the resource region for uplink data to eNodeB. UE2 can send D2D data to UE1 under f2u. Symmetrically, UE1 can operate in receive mode of operation under f2u and UE2 can operate in receive mode of operation under f1u.

Therefore, when UE1 knows the data transmission area of UE2 for D2D communication under f2u, and UE2 knows the data transmission area of UE1 for D2D communication under f1u, it can receive the data for D2D communication sent by the peer UE.

FIG. 12 is a diagram illustrating an example of operating frequency switching for D2D communication according to one embodiment of the present invention. According to the communication operator's payment policy, the UE may be allowed to use the frequency of another communication operator (ie, the operator subscribed by the peer UE) to transmit data. At this time, a payment policy applied when a UE subscribed to another operator uses an operator frequency is negotiated in advance between operators.

In this case, when a UE that will transmit data for D2D communication detects a peer UE operating at another operator frequency, the UE may switch the operating frequency to the operator frequency of the peer UE, and Send data at the switched frequency. The same is true when a UE that has received data for D2D communication from a peer UE wishes to send an ACK/NAK in response to the received data or to send data for D2D communication to the peer UE. In contrast, a UE recognizing that there is data for D2D communication to be received does not need to switch its frequency, and may receive data from a peer UE in a resource region allocated for receiving D2D communication.

More specifically, the operation of UE and eNodeB will now be described. When the eNodeB acquires information that the UE and the peer UE detect each other, the eNodeB allocates resources for D2D communication (ie, a D2D cycle) to the UE and the peer UE. The D2D cycle may include information on frequency switching times that may occur according to different transmission/reception frequency bands. When the UE that will send data acquires the D2D cycle from the eNodeB, the UE switches its operating frequency to that of the peer UE, and then directly sends the data to the peer UE via the link. Information on the ID and operating frequency of the peer UE may be pre-acquired via the eNodeB, and may be transmitted as an aid in the D2D cycle. The information on the D2D cycle may include control information of data transmission/reception time. At this time, the UE may transmit data to the peer UE at a transmit time (period), and return its operator frequency and receive data and ACK/NAK from the peer UE at a receive time (period).

When a UE recognizing that there is a peer UE wishing to transmit data acquires information on the D2D cycle from the eNodeB, data is received from the peer UE at a reception time (period) of the D2D cycle. When the data is successfully received at the receive time, the UE may switch its frequency to the operator frequency of the peer UE, sending ACK and data to the peer UE. When no data is received at the receive time, the UE may switch its frequency to the operator frequency of the peer UE at the transmit time and then send an ACK or wait for the next receive time.

In FIG. 11 , the UE performs a transmit operation on its operator frequency and a receive operation on the UE's operator frequency. In contrast, in Figure 12, the UE performs receive operations on its operator frequency and transmit operations on the peer UE's operator frequency.

FIG. 13 is a diagram illustrating an example of synchronization in a D2D cycle according to one embodiment of the present invention. FIG. 13 shows the setting of the D2D period when the frequency of the transmission operation and the frequency of the reception operation are different like in the embodiments shown in FIGS. 11 to 12 . UE1 and UE2 use the D2D communication method to send data. When the frequency of the sending operation is different from that of the receiving operation, UE2 should be set to perform the receiving operation during the period in which UE1 performs the sending operation. This can be configured by the eNodeB in the D2D setup process. UE1 can transmit data to UE2 in the uplink frequency region f1u of eNodeB1, and UE2 can receive data from UE1 in the uplink frequency region f1u of eNodeB1. When the transmitting operation period of UE1 ends, UE1 may switch its operating frequency to the uplink frequency f2u of UE2, and perform receiving operation during this period. This operating frequency or transmission/reception operation mode switching time is referred to as switching time.

In addition, UE1 (or UE2) can dynamically determine the frequency switching time. For example, there is a method for transmitting data at UE1 at the operating frequency of UE2 (peer UE), followed by a channel switch request. UE1 may return to its operating frequency after sending the channel switching request, and the UE receiving the channel switching request may switch its frequency to the operating frequency of UE1.

The transmission/reception time of each UE shown in FIG. 13 can be pre-defined through negotiation between eNodeBs. For example, when eNodeB1 determines UE1's transmission time and transmits it to eNodeB2, eNodeB2 can set the transmission time as its reception time, and determine an appropriate time corresponding to UE1's transmission time as UE2's transmission time and set it as its reception time. sent to eNodeB1. Here, the appropriate time is within a range such that the delay is not excessively long while securing the minimum time required for decoding ACK/NACK. At this time, the range may be predefined or predetermined through negotiation between eNodeBs. As the negotiated transmission time (or reception time) information, the D2D transmission and reception cycle value may be notified to the UE in the D2D setting process.

Fig. 14 shows a simple example of determining D2D transmission/reception time via negotiation between eNodeBs. The eNodeB1 may set the subframe (SF) #10n+5 as the D2D transmission time (n>=0) in the uplink frequency band f1u of the UE1. When the set transmission time is transmitted to the eNodeB, the eNodeB2 may switch the time set as the transmission time of the UE1 in the uplink frequency band f1u of the UE1, and set the SF corresponding thereto as the D2D reception time. Then, eNodeB2 can select and set an appropriate time under the uplink frequency band f2u of UE2 as the sending time of UE2, and then send the response to eNodeB1. In FIG. 14 , based on UE1 in the frequency band f1u, the time corresponding to SF#10n (n>=1) can be set by eNodeB2 as the transmission time of UE2.

When receiving information about UE2's transmission time from eNodeB2, eNodeB1 may switch and set this time as the D2D reception time under f2u. At this time, since the symbol synchronization at each operator frequency may be different, the symbol difference and timing advance between the sending UE and the receiving UE are considered (for convenience of description, these two are not shown in FIG. 14 ).

The transmission SF position set by eNodeB2 according to the transmission time set by eNodeB1 can be determined as predetermined m SFs after the transmission time set by eNodeB1 (m=5 in FIG. 10 ). In this case, the transmission/reception time of all eNodeBs is determined by setting the transmission time of eNodeB1, and the eNodeB may not transmit a response. For synchronization between D2D UEs, synchronization information of radio frames/subframes between eNodeBs and timing advance information of each UE should be exchanged. This information may be conveyed when information about the time of transmission (or time of reception) is exchanged between eNodeBs, or may be conveyed via a separate message or pre-exchanged.

As described above, the information on the D2D resource region transmitted from the eNodeB to the UE may be transmitted via RRC signaling or a control channel. When transmitting information via RRC signaling, if one transmission (reception) time is determined according to a predetermined rule and then another reception (transmission) time is determined, only the transmission resource region and cycle may be transmitted as in the above-described D2D cycle. In contrast, if the transmit/receive time does not follow specific rules, but can be changed by the eNodeB's decision, a 1-bit indicator for distinguishing between transmit mode and receive mode can be added to the D2D cycle to determine Whether the resource area is allocated for transmission or reception. When resource allocation is performed via a control channel, different control message formats/identifiers (RNTIs) may be used.

15 and 16 are diagrams illustrating a D2D setting and communication process according to one embodiment of the present invention. FIG. 15 is similar to the process of FIG. 7 . Unlike FIG. 7 , a D2D Setup Response message may be sent to a peer UE (ie, UE 260 ) that does not send a D2D Setup Request message, and resource negotiation for D2D communication may be performed between eNodeBs before sending the D2D Setup Response message. Repetition of the same description will be omitted.

When receiving the D2D setup request message from the UE 110 ( S1501 ), the eNodeB 120 may perform resource negotiation for D2D communication with the eNodeB (ie, eNodeB 250 ) of the UE 220 (peer UE of the UE 110 ) ( S1502 ). That is, an operator frequency to be used for D2D communication may be determined through resource negotiation between eNodeBs. At this time, UE capability, available D2D resource area, D2D load, etc. may be considered. For example, in UE capabilities, if UE1 can operate under f1 and f2, but UE260 can only operate under f2, then in the negotiation process between eNodeBs, the operator frequency f2 of UE2 can be determined to be used for D2D communication working frequency. Even in the available D2D resource area, if the operator of UE260 does not individually allocate a resource area for D2D communication or the resources that can be allocated by eNodeB250 for additional D2D pairs are relatively insufficient compared with the resources of eNodeB120, the operator frequency of UE110 Can be determined as an operating frequency for D2D communication.

The D2D Setup Response message may be transmitted to both the UE110 and UE260 (peer UEs) that transmitted the D2D Setup Request message (S1503-1 and S1503-2). At this time, the information about the D2D cycle and the D2D resource region transmitted to the UE should be consistent with each other. For agreement of resource areas, as described above, a predetermined value may be used, or a value determined through data exchange and resource negotiation between eNodeBs may be used.

The D2D setup response message indicates an operator frequency to be used for D2D data communication. The UE having received the D2D Setup Response message switches to the operator frequency, and then receives the control channel at the operator frequency. If the same operator frequency equal to the operating frequency of the UE is used, the frequency is not switched, and the resource region where the control channel for D2D communication is transmitted is monitored to receive the control channel.

In the embodiment related to FIG. 15 , since the operator frequency of UE260 (peer UE of UE110 sending the D2D setup request message) is used for D2D communication, UE110 switches its operating frequency to the operating frequency f2 of UE260 (S1504) , UE220 does not switch its operating frequency. After the frequency switching, the UE110 and the UE260 may receive a D2D control channel (or D2D PDCCH) from the second eNodeB 50 (S1505-1 and S1505-2), and perform D2D communication (S1506).

In the embodiment of FIG. 16 , contrary to FIG. 15 , the operator frequency of the UE 110 transmitting the D2D setup request message is used for D2D communication.

FIG. 17 is a diagram illustrating a resource renegotiation procedure for D2D setup, D2D communication, and D2D communication between eNodeBs according to one embodiment of the present invention. Steps S1701 to S1706 of FIG. 17 are equal to steps S1501 to S1506 of FIG. 15 , and description thereof will be omitted.

The UE receiving the D2D Setup Response message should monitor and receive the D2D Control Channel (or D2DPDCCH) in order to perform data communication with the peer UE. Specifically, a UE that switches its frequency may receive a control channel at the switched frequency. However, when the eNodeB notifies the UE of the transmission resource region for D2D communication via the D2D Setup Response message, data transmission and reception may be performed in the region specified in the D2D Setup Response message without receiving the control channel after channel switching. That is, each UE receives resource region information for D2D communication from each serving eNodeB. At this time, if the resource region information is for the operator frequency of the peer-to-peer UE, the UE switches its operating frequency to the operator frequency to perform D2D communication.

For example, when determining an operating frequency for D2D communication, a resource region for D2D communication may be determined according to a predetermined rule, or a resource region to be used may be pre-designated according to operator frequency or eNodeB. However, even in this case, the UE's operating frequency and transmission and reception times may be renegotiated between eNodeBs.

In addition, when resources are allocated dynamically, the frequency is switched every time the D2D resource area changes, and thus, a signal related thereto should be received. That is, a UE operating under the operator frequency of the peer UE should periodically switch its operating frequency to the operator frequency in order to be allocated a D2D resource region. In contrast, since a UE includes a plurality of receivers, if each receiver is available for D2D communication and simultaneously communicates with a serving eNodeB, the UE may not periodically switch its frequency.

When a resource region for D2D communication is determined through renegotiation, each eNodeB transmits a D2D Setup Response message to the UE 110 and UE 260 served by it to inform the UEs of information thereon. In the embodiment of FIG. 17, since the operating frequency for D2D communication is switched via renegotiation, each UE may switch its operating frequency based on the operating frequency information included in the D2D Setup Response message (1709-1 and S1709- 2).

Before the D2D setup request processing, the eNodeB may request D2D discovery to the UE pair. This is a process at the UE that sends a signal via a radio channel to a peer UE to check that the UE is within D2D communication range. For example, in FIG. 7, the eNodeB requests the UE to send a predetermined discovery signal in a specific resource region, and requests the peer UE to scan for the predetermined discovery signal in the same resource region. At this time, similar to the determination of the D2D operating frequency and resource area in the D2D setup process, the selection of the operator frequency and resource area for sending the discovery signal may take into account UE capabilities, available D2D resources, etc. via eNodeB or negotiation between operators. Region, D2D load, etc. to determine.

For example, if the eNodeB reserves predetermined resources to be used for discovery signals in UE1's cell, but no predetermined resources are reserved in UE2's cell to be used for discovery signals because there are no D2D UEs, UE2 may move to UE1's cell to perform the discovery process. However, information on transmission and reception should be transmitted so that a UE receiving the information determines whether to transmit or receive a discovery signal, and determines whether its operating frequency is switched.

In addition, since resource negotiation is performed in the step of transmitting a discovery signal, the D2D setup response message may not include working operator frequency information in the D2D setup step. This is because the process of switching the UE's frequency to use the same operator frequency and then switching the frequency used for data transmission can be wasteful. Specifically, if a discovery process between UEs is performed first, the D2D setup request message may report the result of the discovery process to the eNodeB. Only when the UE successfully receives the discovery signal of the peer UE, the next D2D setup procedure may be performed.

FIG. 18 is a block diagram of an apparatus for performing operations related to D2D communication according to an exemplary embodiment of the present invention. The transmitting device 10 and the receiving device 20 comprise radio frequency (RF) units 13 and 23, respectively, for transmitting and receiving radio signals carrying information, data, signals and/or messages, for storing information related to communications in a wireless communication system The memories 12 and 22, and operatively connected to the RF units 13 and 23 and the memories 12 and 22 and configured to control the memories 12 and 22 and/or the RF units 13 and 23 to perform at least one of the above-described embodiments of the present invention processors 11 and 21.

The memories 12 and 22 can store programs for processing and controlling the processors 11 and 21, and can temporarily store input/output information. The memories 12 and 22 may be used as buffers.

The processors 11 and 21 control the overall operations of various modules in the transmitting device 10 or the receiving device 20 . Processors 11 and 21 can perform various control functions to realize the present invention. Processors 11 and 21 may be controllers, microcontrollers, microprocessors or microcomputers. The processors 11 and 21 may be realized by hardware, firmware, software or a combination thereof. In the hardware configuration, the processors 11 and 21 may include Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs) or Field Programmable Gate Arrays ( FPGA). If the present invention is implemented using firmware or software, the firmware or software may be configured to include modules, procedures, functions, etc. that perform the functions or operations of the present invention. Firmware or software configured to execute the present invention may be included in the processors 11 and 21 or stored in the memories 12 and 22 to be driven by the processors 11 and 21 .

The processor 11 of the transmission device 10 schedules from the processor 11 or a scheduler connected to the processor 11, and encodes and modulates a signal and/or data to be transmitted to the outside. The encoded and modulated signals and/or data are sent to the RF unit 13 . For example, the processor 11 converts the data stream to be sent into K layers through demultiplexing, channel coding, scrambling and modulation. An encoded data stream is also called a codeword and is equivalent to a transport block (a data block provided by the MAC layer). One transport block (TB) is encoded into one codeword, and each codeword is transmitted to a receiving device in the form of one or more layers. For up-conversion, the RF unit 13 may include an oscillator. The RF unit 13 may include Nt transmit antennas (where Nt is a positive integer).

The signal processing procedure of the receiving device 20 is the reverse procedure of the signal processing procedure of the transmitting device 10 . Under the control of the processor 21 , the RF unit 23 of the receiving device 10 receives the RF signal transmitted by the transmitting device 10 . The RF unit 23 may include Nr receiving antennas, and down-converts respective signals received through the receiving antennas into baseband signals. The RF unit 23 may include an oscillator for frequency down conversion. The processor 21 decodes and demodulates radio signals received through the receiving antenna, and restores data that the transmitting device 10 wishes to transmit.

The RF units 13 and 23 include one or more antennas. The antenna performs a function of transmitting signals processed by the RF units 13 and 23 to the outside or receiving radio signals from the outside to transmit the radio signals to the RF units 13 and 23 . Antennas may also be referred to as antenna ports. Each antenna may correspond to one physical antenna, or may be configured by a combination of more than one physical antenna element. Signals transmitted through the respective antennas cannot be decomposed by the receiving device 20 . A reference signal (RS) transmitted by an antenna defines the corresponding antenna as viewed from the receiving device 20 and enables the receiving device 20 to perform channel estimation for that antenna, regardless of whether the channel is from a single RF channel of one physical antenna or from multiple RF channels comprising the antenna. composite channel of physical antenna elements. That is, the antennas are defined such that a channel on which a symbol is transmitted on an antenna is derived from a channel on which another symbol is transmitted on the same antenna. An RF unit supporting a MIMO function for transmitting and receiving data using multiple antennas may be connected to two or more antennas.

In an embodiment of the present invention, a UE functions as a transmitting device 10 on the uplink and as a receiving device 20 on the downlink. In an embodiment of the present invention, the eNB functions as the receiving means 20 on the uplink and as the transmitting means 10 on the downlink.

A specific configuration of a UE or an eNB functioning as a transmitting device and/or a receiving device may be configured as a combination of one or more embodiments of the present invention.

The detailed description of the exemplary embodiments of the present invention has been given to enable those skilled in the art to realize and practice the invention. Although the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various modifications and changes can be made therein without departing from the spirit or scope of the invention as described in the appended claims. For example, those skilled in the art can use the respective configurations described in the above embodiments in combination with each other. Thus, the invention should not be limited to the particular embodiments described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Industrial Applicability

The present invention is applicable to wireless communication devices such as UEs, relays, eNBs and the like.

Claims (18)

1. for locating with the 2nd UE final controlling element device (D2D) method of communicating by letter at first user equipment (UE) at wireless communication system, the method comprises the following steps:

From base station, receive the D2D communications setting response message comprising for the resource area information of D2D communication;

Based on described resource area information, determine whether the working band of a described UE to be switched to the second frequency band from the first frequency band; And

According to definite result, in described the first frequency band or described the second frequency band, carry out described D2D with described the 2nd UE and communicate by letter,

Wherein, a transmission for described D2D communication in described the first frequency band or described the second frequency band, another is for the reception of described D2D communication.

2. method according to claim 1 wherein, is carried out the transmission of described D2D communication in described the first frequency band, carries out the reception of described D2D communication in described the second frequency band.

3. method according to claim 1 wherein, is carried out the transmission of described D2D communication in described the second frequency band, carries out the reception of described D2D communication in described the first frequency band.

4. method according to claim 1, wherein, described resource area information comprises the information of the frequency of communicating by letter with described D2D about the cycle of described D2D communication.

5. method according to claim 1, wherein, working band described in time-switching when the switching between the send and receive of described D2D communication occurs for a described UE or described the 2nd UE, the described time is indicated by the information that is included in the cycle about described D2D communication in described resource area information.

6. method according to claim 1, the method is further comprising the steps of: described working band is switched to described the second frequency band by described resource area information indication.

7. method according to claim 1, wherein, the step of carrying out described D2D communication is further comprising the steps of: monitoring is for the control channel of described D2D communication, and receives receiving control information or send control information.

8. method according to claim 1, wherein, described D2D communications setting response message also comprises about the search volume of control channel and the information of scrambling identifier for described D2D communication.

9. be configured to a UE who with peer user devices (UE) final controlling element, device (D2D) is communicated by letter in wireless communication system, this UE comprises:

Radio frequency (RF) unit, this RF unit is configured to send or receive RF signal; And

Processor, this processor is configured to control described RF unit,

Wherein, described processor is configured to receive from base station via described RF unit the D2D communications setting response message comprising for the resource area information of D2D communication, based on described resource area information, determine whether the working band of described UE to be switched to the second frequency band from the first frequency band, and according to definite result, in described the first frequency band or described the second frequency band, carry out described D2D with described reciprocity UE and communicate by letter, and

Wherein, a transmission for described D2D communication in described the first frequency band or described the second frequency band, another is for the reception of described D2D communication.

10. UE according to claim 9 wherein, carries out the transmission of described D2D communication in described the first frequency band, carries out the reception of described D2D communication in described the second frequency band.

11. UE according to claim 9 wherein, carry out the transmission of described D2D communication in described the second frequency band, carry out the reception of described D2D communication in described the first frequency band.

12. UE according to claim 9, wherein, described resource area information comprises the information of the frequency of communicating by letter with described D2D about the cycle of described D2D communication.

13. UE according to claim 9, wherein, working band described in time-switching when the switching between the send and receive of described D2D communication occurs for a described UE or described the 2nd UE, the described time is indicated by the information that is included in the cycle about described D2D communication in described resource area information.

14. UE according to claim 9, wherein, described working band is switched to described the second frequency band by described resource area information indication.

15. UE according to claim 9, wherein, described processor is configured to monitoring for the control channel of described D2D communication, and receives receiving control information or send control information.

16. UE according to claim 9, wherein, described D2D communications setting response message also comprises about the search volume of control channel and the information of scrambling identifier for described D2D communication.

17. 1 kinds of methods for device (D2D) being communicated by letter with the device between the 2nd UE at base station place's support first user equipment (UE) at wireless communication system, the method comprises the following steps:

The D2D communications setting response message that comprises the resource area information of communicating by letter for D2D is sent to a described UE or described the 2nd UE,

Wherein, described resource area information comprises the first frequency band that the working band about communicating by letter with D2D is corresponding and the information of the second frequency band,

Wherein, a transmission for described D2D communication in described the first frequency band or described the second frequency band, another is for the reception of described D2D communication.

18. 1 kinds are configured to the base station of supporting that in wireless communication system first user equipment (UE) is communicated by letter to device (D2D) with the device between the 2nd UE, and this base station comprises:

Radio frequency (RF) unit, this RF unit is configured to send or receive RF signal; And

Processor, this processor is configured to control described RF unit,

Wherein, described processor is configured to, via described RF unit, the D2D communications setting response message that comprises the resource area information of communicating by letter for D2D is sent to a described UE or described the 2nd UE,

Wherein, described resource area information comprises the first frequency band that the working band about communicating by letter with described D2D is corresponding and the information of the second frequency band, and

Wherein, a transmission for described D2D communication in described the first frequency band or described the second frequency band, another is for the reception of described D2D communication.